diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 73ae71c..e9c0fdd 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -1312,8 +1312,8 @@
             m_Syntax.RestorePos(SavedPos);
             return;
         }
-        FX_DWORD real_objnum = FXSYS_atoi(word);
-        if (real_objnum && real_objnum != objnum) {
+        FX_DWORD parser_objnum = FXSYS_atoi(word);
+        if (parser_objnum && parser_objnum != objnum) {
             m_Syntax.RestorePos(SavedPos);
             return;
         }
@@ -1377,8 +1377,8 @@
     }
     FX_FILESIZE objOffset = m_Syntax.SavePos();
     objOffset -= word.GetLength();
-    FX_DWORD real_objnum = FXSYS_atoi(word);
-    if (objnum && real_objnum != objnum) {
+    FX_DWORD parser_objnum = FXSYS_atoi(word);
+    if (objnum && parser_objnum != objnum) {
         m_Syntax.RestorePos(SavedPos);
         return NULL;
     }
@@ -1387,21 +1387,23 @@
         m_Syntax.RestorePos(SavedPos);
         return NULL;
     }
-    FX_DWORD gennum = FXSYS_atoi(word);
+    FX_DWORD parser_gennum = FXSYS_atoi(word);
     if (m_Syntax.GetKeyword() != FX_BSTRC("obj")) {
         m_Syntax.RestorePos(SavedPos);
         return NULL;
     }
-    CPDF_Object* pObj = m_Syntax.GetObject(pObjList, objnum, gennum, 0, pContext);
+    CPDF_Object* pObj = m_Syntax.GetObject(pObjList, objnum, parser_gennum, 0, pContext);
     FX_FILESIZE endOffset = m_Syntax.SavePos();
     CFX_ByteString bsWord = m_Syntax.GetKeyword();
     if (bsWord == FX_BSTRC("endobj")) {
         endOffset = m_Syntax.SavePos();
     }
     m_Syntax.RestorePos(SavedPos);
-    if (pObj && !objnum) {
-        pObj->m_ObjNum = real_objnum;
-        pObj->m_GenNum = gennum;
+    if (pObj) {
+        if (!objnum) {
+            pObj->m_ObjNum = parser_objnum;
+        }
+        pObj->m_GenNum = parser_gennum;
     }
     return pObj;
 }
@@ -1416,8 +1418,8 @@
         m_Syntax.RestorePos(SavedPos);
         return NULL;
     }
-    FX_DWORD real_objnum = FXSYS_atoi(word);
-    if (objnum && real_objnum != objnum) {
+    FX_DWORD parser_objnum = FXSYS_atoi(word);
+    if (objnum && parser_objnum != objnum) {
         m_Syntax.RestorePos(SavedPos);
         return NULL;
     }
@@ -3466,8 +3468,8 @@
     if (!bIsNumber) {
         return NULL;
     }
-    FX_DWORD real_objnum = FXSYS_atoi(word);
-    if (objnum && real_objnum != objnum) {
+    FX_DWORD parser_objnum = FXSYS_atoi(word);
+    if (objnum && parser_objnum != objnum) {
         return NULL;
     }
     word = m_syntaxParser.GetNextWord(bIsNumber);
diff --git a/core/src/fxcrt/fx_basic_gcc.cpp b/core/src/fxcrt/fx_basic_gcc.cpp
index 7f5bbad..93c71ce 100644
--- a/core/src/fxcrt/fx_basic_gcc.cpp
+++ b/core/src/fxcrt/fx_basic_gcc.cpp
@@ -4,6 +4,7 @@
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
+#include <limits>
 #include "../../include/fxcrt/fx_ext.h"
 template <class T, class STR_T>
 T FXSYS_StrToInt(STR_T str)
@@ -21,6 +22,9 @@
         if ((*str) < '0' || (*str) > '9') {
             break;
         }
+        if (num > (std::numeric_limits<T>::max() - 9) / 10) {
+            break;
+        }
         num = num * 10 + (*str) - '0';
         str ++;
     }